The present invention relates to an arrangement for retaining the reactor internals holddown spring forming a component installed in a nuclear reactor pressure vessel.
Various types of pressurized water reactors include, within a pressure vessel, a core barrel, an inner barrel and an upper calandria, each provided with an upper, outwardly extending flange via which the respective part is supported within the pressure vessel. An annular holddown spring is associated with these components and the highest structural margins and reliability are achieved when the spring is positioned between the inner barrel flange and the core barrel flange.
However, in a recently proposed new pressurized water reactor design, the region of the core barrel flange which would be covered by the holddown spring is provided with components which must be accessible at various times, particularly during refueling and inservice inspection. Individual removal of the holddown spring is extremely difficult.
It might be possible to eliminate this problem by installing the holddown spring between the flanges of the inner barrel and the upper calandria, so that the spring could be lifted together with the inner barrel. However, this location presents a number of drawbacks, including the fact that it will result in lower reliability and higher spring loads.